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Diffstat (limited to 'rpc/doc.go')
-rw-r--r-- | rpc/doc.go | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/rpc/doc.go b/rpc/doc.go new file mode 100644 index 0000000..e5840c3 --- /dev/null +++ b/rpc/doc.go @@ -0,0 +1,118 @@ +// Copyright 2015 The go-ethereum Authors +// This file is part of the go-ethereum library. +// +// The go-ethereum library is free software: you can redistribute it and/or modify +// it under the terms of the GNU Lesser General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// The go-ethereum library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Lesser General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public License +// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. + +/* + +Package rpc implements bi-directional JSON-RPC 2.0 on multiple transports. + +It provides access to the exported methods of an object across a network or other I/O +connection. After creating a server or client instance, objects can be registered to make +them visible as 'services'. Exported methods that follow specific conventions can be +called remotely. It also has support for the publish/subscribe pattern. + +RPC Methods + +Methods that satisfy the following criteria are made available for remote access: + + - method must be exported + - method returns 0, 1 (response or error) or 2 (response and error) values + - method argument(s) must be exported or builtin types + - method returned value(s) must be exported or builtin types + +An example method: + + func (s *CalcService) Add(a, b int) (int, error) + +When the returned error isn't nil the returned integer is ignored and the error is sent +back to the client. Otherwise the returned integer is sent back to the client. + +Optional arguments are supported by accepting pointer values as arguments. E.g. if we want +to do the addition in an optional finite field we can accept a mod argument as pointer +value. + + func (s *CalcService) Add(a, b int, mod *int) (int, error) + +This RPC method can be called with 2 integers and a null value as third argument. In that +case the mod argument will be nil. Or it can be called with 3 integers, in that case mod +will be pointing to the given third argument. Since the optional argument is the last +argument the RPC package will also accept 2 integers as arguments. It will pass the mod +argument as nil to the RPC method. + +The server offers the ServeCodec method which accepts a ServerCodec instance. It will read +requests from the codec, process the request and sends the response back to the client +using the codec. The server can execute requests concurrently. Responses can be sent back +to the client out of order. + +An example server which uses the JSON codec: + + type CalculatorService struct {} + + func (s *CalculatorService) Add(a, b int) int { + return a + b + } + + func (s *CalculatorService) Div(a, b int) (int, error) { + if b == 0 { + return 0, errors.New("divide by zero") + } + return a/b, nil + } + + calculator := new(CalculatorService) + server := NewServer() + server.RegisterName("calculator", calculator") + + l, _ := net.ListenUnix("unix", &net.UnixAddr{Net: "unix", Name: "/tmp/calculator.sock"}) + for { + c, _ := l.AcceptUnix() + codec := v2.NewJSONCodec(c) + go server.ServeCodec(codec, 0) + } + +Subscriptions + +The package also supports the publish subscribe pattern through the use of subscriptions. +A method that is considered eligible for notifications must satisfy the following +criteria: + + - method must be exported + - first method argument type must be context.Context + - method argument(s) must be exported or builtin types + - method must have return types (rpc.Subscription, error) + +An example method: + + func (s *BlockChainService) NewBlocks(ctx context.Context) (rpc.Subscription, error) { + ... + } + +When the service containing the subscription method is registered to the server, for +example under the "blockchain" namespace, a subscription is created by calling the +"blockchain_subscribe" method. + +Subscriptions are deleted when the user sends an unsubscribe request or when the +connection which was used to create the subscription is closed. This can be initiated by +the client and server. The server will close the connection for any write error. + +For more information about subscriptions, see https://github.com/ethereum/go-ethereum/wiki/RPC-PUB-SUB. + +Reverse Calls + +In any method handler, an instance of rpc.Client can be accessed through the +ClientFromContext method. Using this client instance, server-to-client method calls can be +performed on the RPC connection. +*/ +package rpc |